All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
The Ahlul-Bayt are Bani Haashim and Bani Abdul-Muttalib. The evidence for this is the Hadeeth (narration) reported from Imaam Al-Bukhari that the Prophet said: "Indeed, Banu Al-Muttalib and Banu Haashim are the same." Ahlul-Bayt also include the wives of the Prophet as Allaah The Almighty Says (what means): {… Allaah wishes only to remove Ar-Rijs (evil deeds and sins, etc.) from you, O members of the family (of the Prophet ), and to purify you with a thorough purification.} [Quran, 3:33]
Ibn Katheer interpreted this verse by saying, “This is an evidence that the wives of the Prophet are among the Ahlul-Bayt, as this verse is about them.”
Allaah Knows best.